XSEED has a number of Japanese franchises under their belt, but some are bigger than others. In an interview with GamesBeat, XSEED's Ken Berry is asked about the top franchise the company has right now, and he believes it to be Rune Factory. Apparently the franchise is still doing considerable business on the 3DS as well!
I’d say it may have to be Rune Factory right now. Based on the great success that Rune Factory 4 had on the 3DS, we ended up doing more than 250,000 units, between physical and digital, since it launched in 2013. And even now we’re shipping more 3DS product of Rune Factory 4, and then the upcoming Rune Factory 4 Special, the HD remake for the Switch, there’s a lot of excitement about that. So I’d say is our biggest franchise right now.